I've been using CY56777 BLE4.2 USB Dongle with Cysmart 1.2 to communicate with my BLE 4.2 devices, I've detected that the max range is around 10m although I read in other comments that this max range is 30 m.

I would like to know if I'm doing something wrong or my results are correct.

The range in wireless devices is hard to gauge effectively due to constructive and deconstructive interference. Thus, there is only a minimum range on wireless specs usually, with a typical/expected range value given. Varying different test locations/settings might change the range you are seeing: Indoors, outdoors, narrow hallway, corner of room versus center of room, lots of metal/conductors/wireless devices nearby, etc.